1. Field of the Invention
The present invention relates to a Schottky barrier diode and a method of manufacturing thereof, and more particularly, to a Schottky barrier diode having improved rectifying characteristics and a method of manufacturing thereof.
2. Description of the Background Art
FIG. 1 schematically shows a sectional view of a conventional Schottky barrier diode. Referring to FIG. 1, this diode has an ohmic metal electrode 20 and a Schottky metal electrode 30 provided on the bottom surface and the top surface, respectively, of a semiconductor substrate 10 having a plate configuration.
In a Schottky barrier diode utilizing rectifying characteristics by means of a metal/semiconductor junction, a depletion layer 11 is formed in the semiconductor in proximity to the metal/semiconductor junction interface so as to generate a built-in voltage, so that the Fermi level on both sides of the metal/semiconductor junction interface is identical. Since there are no charge carriers such as electrons and holes in depletion layer 11, it is necessary to lower the potential barrier height of depletion layer 11 by applying a forward voltage opposing the built-in voltage in order to obtain a forward current between Schottky electrode 30 and ohmic electrode 20. The forward voltage applied to lower the potential barrier height of depletion layer 11 is equivalent to the threshold voltage of the diode. Therefore, a forward direction voltage greater than the threshold voltage must be applied to obtain a flow of forward current.
A Schottky barrier diode employing a GaAs substrate has a built-in voltage greater than that of a diode employing a silicon substrate. This built-in voltage does not substantially change even if the type of the metal of the electrode is changed. This means that a Schottky barrier diode employing a GaAs substrate has rectifying characteristics in the forward direction inferior to those of one employing a silicon substrate.
A typical threshold voltage of a Schottky barrier diode using a GaAs substrate is 0.6 V. A forward voltage exceeding the threshold voltage of 0.6 V must be applied to establish a flow of forward current. If a forward voltage of 0.9 V, for example, is applied to establish a flow of forward current I, 0.6 V.times.I is consumed as power loss. Two thirds of the entire consumed power 0.9 V.times.I is spent as the power loss by the threshold voltage and is converted into undesired heat.